North American Delphiniums from seed.

[Giles]

Closely related to the Aconitum question..  ..I wondered if species of North American delphiniums were best sown now, in Winter, or in the Spring..
..and then there's the European and Chinese ones, too..

[Robert]

Giles,

I can not offer advice for other species, however I do sow the California Delphinium species 15 October. Fresh seed brings excellent results the following spring.

Perhaps another good question is how to handle them the following spring-summer before they go into dormancy. Many, but not all, are not tolerant of summer moisture and the dormant "bulbs" or perennial roots will rot if not dealt with properly. If started on time and dealt with properly many will bloom in the spring from a fall sowing. At least those are my results with our climatic conditions.

[Maggi Young]

Giles,

I can not offer advice for other species, however I do sow the California Delphinium species 15 October. Fresh seed brings excellent results the following spring.

Perhaps another good question is how to handle them the following spring-summer before they go into dormancy. Many, but not all, are not tolerant of summer moisture and the dormant "bulbs" or perennial roots will rot if not dealt with properly. If started on time and dealt with properly many will bloom in the spring from a fall sowing. At least those are my results with our climatic conditions.

 Very interesting, Robert.  Do the dormant  roots need to be lifted, or  is a cover sufficient?

[Robert]

Maggi,

The issue is getting the dry-land Delphinium species through the summer dry season. In my experience, seedlings need to make as much growth as possible before they go dormant. In addition, the seedlings do not like to be disturbed. To accomplish this I start the seeds in 4" (10cm) square pots. After the seed germinates and the seedlings have 1-2 true leaves, I transplant the contents of the 4" pot of seedlings, intact, into a 01 Gallon nursery container. The 01 Gallon container has a very quick draining planting mix with some time-release fertilizer. This gives the seedlings some extra room and nutrients to make rapid growth.

As the dry season begins and it gets hot, the seedling will begin to brown-out (i.e. go dormant). It is time to reduce watering. When the seedlings are completely dormant I move the 01 Gallon pots to a very shady location where they spend the summer completely dry. I let the natural autumn rains bring the seedlings out of dormancy.

In the early spring the seedlings can be transplanted into individual pots or planted out into the garden. Good timing is important. One wants the seedlings in active growth so that the plants can repair any damage from transplanting. It is also important this is done early enough so that the seedlings can make good growth, hopefully bloom, before going dormant.

This is what works for me with our climatic conditions.

[Giles]

....all useful information, Robert, thankyou.
One of the other things I wondered about, was how cold it got with you?  ..will they need frost protection, either as seedlings in pots, or mature plants in the ground. It doesn't usually get much below -5 / -7 deg C here, but have had -20 in an exceptional year. (-4 in Fahrenheit)

[Maggi Young]

Yes, Robert,  I agree with Giles , very useful information, thank you.

[Robert]

Giles,

Perhaps you will find some of our weather statistics useful. Our farm is at approximately 1,500 feet (457 meters) elevation (in a valley). During the winter we generally always get temperatures of about 20 F (-6.5 C). Sometimes it gets a bit colder. Our all time low temperature is 8 F (-13 C). Over the years the weather has certainly warmed. Back in the 1960's, 70's, and 80's snow was a regular wintertime occurrence. Now some winters we never get snow at all. Even the fruit trees are showing signs of lack of chilling hours some winters.

These temperatures translate to our local native dryland Delphiniums fairly well. This includes Delphinium gracilentum, D. hansenii, D. patens and D. variegatum. Of coarse there are Delphinium species throughout California in many different habitats; coastal, coastal mountains, central valley, foothills, high mountains, and even east side habitats. Then there is the range of species from north to south.

I have not grown any, nor can I think of any, California Native Delphinium species that need frost protection when grown in the ground. Container grown plants are different. Most winters I do not need to provide any protection for the container grown or seeded out seed pans. They all seem to benefit from the cold. When the weather remains below 20 F (-6.5) or more at night, or the daytime temperature stays below 32 F (0 C) for more than 1 or 2 days then protection is very necessary. In the past there could often be snow cover to protect the plants, and this could be enough. However, with extreme cold I have to take other measures to protect the plants. Even very cold hardy high elevation species can die in a frozen pot.

I hope this additional information is helpful. The situation for our native Delphiniums is complex in many ways. Careful study and review pays off.

[Giles]

Robert, Thankyou...